In data processing systems a processor may be coupled to a memory via a system bus. The U.S. Patent Application U.S. 2007/0283115 describes memory protection in a computer system employing memory virtualization. A token based memory protection technique provides memory protection by assigning a unique identifier to an application, process or thread. The identifier is associated with a block of memory allocated to the application. A request to access a memory address may contain a token to be compared to the identifier that is assigned to the address range of the requested address. Hence access to address ranges in the memory is controlled via the token.
A drawback of such a device is that the memory protection is based on comparing the accessed address to the memory ranges as associated to respective identifiers.